Solanum kachinense X.Aubriot & S.Knapp, 2022

Aubriot, Xavier & Knapp, Sandra, 2022, A revision of the " spiny solanums " of Tropical Asia (Solanum, the Leptostemonum Clade, Solanaceae), PhytoKeys 198, pp. 1-270 : 1

22. Solanum kachinense X.Aubriot & S.Knapp sp. nov.

Fig. 37

Diagnosis.

Like Solanum torvum Sw., but differing in the eglandular pubescence of the inflorescence, more highly branched inflorescences, smaller flowers and almost glabrous mature foliage.

Type.

Myanmar. Kachin: Putao District , "North Triangle (Hkinlum)", 29 Jul 1953, F. Kingdon-Ward 21211 (holotype: BM [BM000900353]; isotype: A) .

Description.

Shrubs of unknown height, armed. Stems erect, terete, drying black, prickly and sparsely stellate-pubescent; prickles broad-based, to 1 cm long, 0.8 cm wide at the base, straight, straw-colored; pubescence of mixed sessile and very short-stalked porrect-stellate trichomes, the stalks to 0.1 mm, the rays 6-8, ca. 0.5 mm long, the midpoints to 0.2 mm long, always shorter than the rays; new growth densely stellate-pubescent, mixed sessile and short-stalked porrect-stellate like those of the stems, the trichomes golden, soon deciduous and the stems glabrate; bark of older stems brown or dark brown. Sympodial units difoliate, the leaves geminate, the leaves of a pair only differing in size. Leaves simple, shallowly lobed, the blades 16-22 cm long, 8-11.5 cm wide, ca. 1.5 times longer than wide, elliptic, widest at the middle or just below, chartaceous, discolorous, armed or unarmed; adaxial surface glabrous to sparsely stellate-pubescent along the veins with a few scattered sessile porrect-stellate trichomes, the rays 5-6, ca. 0.5 mm long, the midpoints equal to the rays; abaxial surface similarly but more densely pubescent with mixed sessile and short-stalked porrect-stellate trichomes, the stalks if present less than 0.2 mm long, the trichomes still only along the veins; major veins 6-8 pairs, drying black, very sparsely stellate-pubescent especially abaxially, sometimes armed, the prickles if present 1-3 per face, to 1.5 cm long; base truncate, strongly oblique with the basiscopic side 1-2 cm further along the petiole; margins shallowly lobed, the lobes broadly deltate with acute tips, the sinuses less than halfway to the midrib; apex acute; petioles 1.8-3 cm long, ca. 1/10 as long as the leaf blades, unarmed and glabrous to stellate-pubescent with a few golden porrect-stellate trichomes like those of the stems, drying blackish brown. Inflorescences 3-6 cm long, internodal and lateral, forked to 5-times branched, with 50-60 flowers, many flowers open at any one time, glabrous but sparsely pubescent with porrect-stellate trichomes at the distal ends; peduncle 1.5-4 cm long, glabrate; pedicels 0.5-0.7 cm long, ca. 1 mm in diameter at the base, ca. 1 mm in diameter at the apex, nodding at anthesis, sparsely stellate-pubescent with golden porrect-stellate trichomes like the inflorescence axes, articulated at the base; pedicel closely spaced ca. 1 mm apart or slightly overlapping. Buds elongate and tapering, strongly exserted from the calyx before anthesis. Flowers 5-merous, apparently all perfect. Calyx with the tube 1.5-2 mm long, conical, scarious and irregularly ripping into lobes at anthesis, the lobes 2-3.5 mm long (including the tip), ca. 2 mm wide, deltate with a subulate tip 1.5-2 mm long, sparsely stellate-pubescent like the pedicels, the subulate tip glabrous. Corolla 1.5-1.8 cm in diameter, "purple sometimes white" (fide Kingdon Ward 21211), stellate, lobed nearly to the base or 3/4 of the way to the base, with little interpetalar tissue, the lobes 6.5-8 mm long, 2.5-4 mm wide, spreading or perhaps somewhat reflexed, glabrous adaxially or with a few stellate trichomes along the petal midvein, densely stellate-pubescent abaxially, the trichomes porrect-stellate with 4-8 weak, tangled rays. Stamens equal; anthers 5-5.5 mm long, ca. 1 mm wide, tapering, yellow, poricidal at the tips, the pores directed distally, not elongating to slits with drying; filament tube minute, glabrous; free portion of the filaments ca. 1 mm long, glabrous. Ovary conical, glabrous; style 6-8 mm long, glabrous; stigma clavate, the surfaces minutely papillose. Fruit and seeds not known. Chromosome number: not known.

Etymology.

Solanum kachinense is named in honour of the province of Myanmar where it occurs, and for the Kachin peoples of the region - who generously assisted the Kingdon-Wards while they were collecting in the region.

Distribution

(Fig. 38 ). Solanum kachinense is known only from the type collection, made in northern Myanmar in the drainage of the Mali Kha, one of the eastern tributaries of the Irrawaddy River whose waters are fed by the Himalayan glaciers of Tibet.

Ecology and habitat.

The type specimen indicates S. kachinense is a "village weed of very sour soil" indicating it grows, as do many solanums, in disturbed or open areas; the village of Hkinlum is at approximately 1,200 m elevation in a region where tropical and temperate elements of the flora mix; Kingdon-Ward (1956) characterised the vegetation of Hkinlum as "moist warm temperate evergreen forest. Not subtropical …”

Common names and uses.

Myanmar. "fruits bitter, not eaten" (Kingdon-Ward 21211).

Preliminary conservation status

( IUCN 2019). Data Deficient (DD). Known only from a single collection, data on the distribution and status of S. kachinense is insufficiently known to speculate about its conservation status.

Discussion.

Despite being currently known to us from a single collection, we describe S. kachinense here because it is so distinct, and that future botanists will be encouraged to find more collections because the entity is known to exist. Very often botanists pass by spiny solanums as uninteresting, in part due to the ubiquity of many introduced species such as S. torvum .

Morphologically, S. kachinense is similar to members of the Torva clade (sensu Stern et al. 2011; Aubriot et al. 2016a) with difoliate sympodia and lateral or leaf-opposed inflorescences with many flowers and fruits. It differs from all other Torva clade species in the region ( S. chrysotrichum , S. comitis , S. poka , S. peikuoense , S. pseudosaponaceum , S. torvoideum and S. torvum ) in its glabrate leaves and stems with long (to 1 cm) very broad-based prickles, especially on stems It has larger flowers than the almost sympatric S. pseudosaponaceum (1-1.8 cm in diameter versus 1-1.5 mm). The glandular simple trichomes present on the inflorescence axes of S. torvum (see description in Vorontsova and Knapp 2016 and on Solanaceae Source) are absent in S. kachinense .

The glabrate upper leaf surfaces are similar to those of S. giganteum but the copious scurfy white pubescence of inflorescences, leaf undersides and stems on that species is distinctive; even in more glabrate individuals of S. giganteum the pubescence is of multangulate trichomes, not of porrect-stellate trichomes like those of S. kachinense .

Solanum kachinense was collected on Frank and Jean Kingdon-Ward’s last trip to the drainages of the upper Irrawaddy in Myanmar to collect in the high mountains bordering China. Hkinlum was their base for their forays into the higher mountains collecting rhododendrons, lilies and alpines for the horticultural trade in England. This plant was not mentioned in Kingdon-Ward (1956); it was collected in the hot, wet season between the Kingdon-Ward’s forays into the mountains, spring for flowers and autumn for seeds when they were perhaps a bit fed up with being stuck in a hot, wet village.

Specimens examined.

See Suppl. materials 1-3.

Figures

Figure 37. Solanum kachinense X. Aubriot & S. Knapp - Herbarium specimen (holotype) collected in Myanmar in 1953 (Kingdon-Ward 21211, BM 000900353). Photograph credit: CC-BY, © copyright The Trustees of the Natural History Museum, London.

Figure 38. Distribution of S. kachinense.